This application filed Nov. 9, 1999, is a xc2xa7 371 filing of PCT/BE99/00143, which takes priority from EP 98870253. 6, filed Nov. 13, 1998.
1. Subject of the Invention
The present invention relates to a process for controlling an ionizing radiation generator.
The present invention also relates to the installation for carrying out this process.
2. Technological Background
Devices for generating X rays, alpha rays, gamma rays or other ionizing rays (or radiation) require a control panel which must be placed a sufficient distance away from the source of radiation in order to avoid any danger of excessive irradiation of the operator.
This is particularly true in the field of industrial non-destructive testing by ionizing radiation. In this case, the device is used xe2x80x9cin situxe2x80x9d, for example in a factory or at a work site, that is to say in an environment which varies according to the application.
An X-ray generator, for example, may be a monobloc device or may consist of separate components (power unit, high-voltage cable, X-ray tube) Generally, the control panel is connected to the generator via an electric cable whose length is such that it allows the operator to be far enough away from it.
Often, the length of the cable thus serves as a reference to the operator or installer to know the safe distance at which the operator should be placed.
However, the physical need for this cable may be a major handicap for the operator and/or for other individuals, who may possibly find themselves within the safety distance of the generator.
This is especially the case when the arrangement of other objects at the work site, for example during the checking of welds by X-ray, prevents the operator from maintaining an overall view in the hazard radius around the generator he is controlling. The operator would therefore not always have the possibility of stopping the generator to prevent other individuals from being placed in danger.
Moreover, no device generally prevents the operator from erroneously placing the control panel an insufficient distance away from the generator. He is even prevented from doing so when the arrangement at the site of use does not allow the cable to be extended in a straight line so that it marks the safe distance for him.
The prior art mentions remote-control devices which allow, for reasons of safety or of convenience of use, the operator or user to be distant from the area in which the devices, which may be hazardous, are operating.
Thus, document JP-A-09238962 discloses a diagnostic and treatment system in the field of dentistry. Flows of electronic data are exchanged between a data storage device and various diagnostic devices, including a dental X-ray generator, and treatment devices located in the vicinity of one or more patients. The data exchange is orchestrated by an input/output controller, which is remote-controlled by means of a wireless transmitter/receiver system. The aim of the invention is to make it easier for a dentist or his assistant to manage the data. However, the X rays used in dentistry are of low energy ( less than 70 keV) and the invention does not per se satisfy the safety needs required when working at a work site with ionizing radiation generators whose energy may be, in certain cases, several MeV. Furthermore, the remote control device may be used to control more than one device or instrument.
Also in the medical field, the remote control of a diagnostic installation which can generate ionizing radiation has been disclosed (U.S. Pat. No. 5,081,543). To solve the problem of safety in the event of disruption or interruption of the control signal, it has been proposed to use two data carrier signals simultaneously, such as, for example, an infra-red signal and an ultra-sound signal. Such a device is complex, expensive and relatively unsuitable for an industrial work site environment.
In the field of checking faults, document CN-A-1 087 171 discloses a remote-control device fitted with a transmitter/receiver for remotely controlling an X-ray generator. Although the said invention is intended to protect the operator, nothing is disclosed regarding the operating procedure or the special advantages of the present application.
The remote-control or digital radio-frequency control of electronic equipment is well-known. Document EP-A1-037 238 presents the use of a digital-frequency radio transmitter/receiver system for remotely controlling an industrial appliance. Such an installation allows the operator to save time, where appropriate, by allowing better vision, increased mobility or a more advantageous position. As regards the safety aspect, it allows the operator to be removed from the hazard zones. Transmission checking means are used throughout the said transmission (use of control channels, generation and comparison of parity bits and of identification code).
WO-A-96/37063 presents a secured encrypted radio-frequency transmission, for example for an application such as in opening a garage door. Safety is ensured by means of operations on a code which has a fixed portion and a variable portion. The signal transmitted is amplitude-modulated, demodulated by the receiver and the initial code is restored.
It is also possible, as in WO-95/33328, to radio-control a switching device, with a control unit which simultaneously sends via the transmitter a code specific to the receiver and a code specific to the device to be controlled. The control data is supplied by the user to the control unit by means of a telephone network (touch-key telephone).
In document U.S. Pat. No. 5,077,831, a safety device consists of a transmitter of a high-frequency signal modulated to a code word signal and of a receiver which has an alarm system. In order to protect the transmitter against any unauthorized use, the said transmitter is provided with a switching system with a memory for entering the code words and an input unit for introducing a password. This password is compared in a comparator with the code words in the memory. If there is a match, the transmission is authorized and the alarm may be actuated.
3. Aims of the Invention
The present invention is directed towards proposing a process for controlling an ionizing radiation generator which ensures a very high level of safety, avoids the aforementioned drawbacks and provides other advantages which will be described below.
A further aim of the present invention is to propose an installation for carrying out this process, which provides many advantages as regards work site safety and management.